So now let's discuss the cranial nerves that are going to extend from our cranium.
There are 12 cranial nerves. And we remember them by using the mnemonic,
"On Old Olympus's Towering Top A Finn And German Viewed A Hop."
These correspond to the different cranial nerves. Cranial nerve one is the olfactory nerve.
Cranial nerve two is the optic nerve. Cranial nerve three is the oculomotor nerve.
Cranial nerve four is the trochlear nerve. Cranial nerve five is the trigeminal nerve.
Cranial nerve six is the abducens nerve. Cranial nerve seven is the facial nerve.
Cranial nerve eight is actually the vestibulocochlear,
but it used to be called the auditory nerve
and so that is why it's an A instead of a V in our mnemonic.
Cranial nerve nine is our glossopharyngeal nerve. Cranial nerve 10 is the vagus nerve.
Cranial nerve 11 is our accessory nerve.
And finally, cranial nerve 12 is the hypoglossal nerve.
So if we look at all of these different cranial nerves,
we'll notice that some of them are sensory nerves.
Others are motor nerves and some have both sensory and motor activity.
Starting with cranial nerve one or the olfactory nerve.
This is a sensory nerve that is responsible for our sense of smell.
Cranial nerve two or the optic nerve is also a sensory nerve
and this is going to be responsible for our sense of sight.
Cranial nerve three is a motor nerve and it is an ocular motor nerve.
This motor nerve is responsible for our eyeball movements
as well as adjusting the lens and pupil constriction.
Cranial nerve four is our trochlear nerve.
It works with cranial nerve three in order to help move the eyeball.
Cranial nerve five is our trigeminal nerve.
This is a mix nerve that has both sensory and motor functions.
For sensory, it is going to include the senses of touch, pain and thermal sensation in our mouth,
our tongue and parts of our face.
Our motor functions from the trigeminal nerve include that of chewing.
The abducens nerve or cranial nerve six is also a motor nerve.
It actually works with cranial nerve three and four,
the ocular motor and the trochlear nerve to move the eyeball.
Cranial nerve seven is the facial nerve.
This is also a mixed nerve that has both sensory and motor functions.
On the sensory side, it's going to send stimuli for taste, touch,
pain and thermal sensation in the mouth and on the face.
And for motor function, it is going to send out motor input to muscles for facial expression
as well as to the salivary gland and the lacrimal glands in order for secretion of saliva and tears.
Cranial nerve eight is the vestibulocochlear nerve.
Vestibulocochlear nerve is a sensory nerve that is responsible for hearing in equilibrium.
Cranial nerve nine is our glossopharyngeal nerve.
This also is a mixed nerve that has both sensory and motor areas.
The sensory nerves are gonna be responsible for taste,
swallowing proprioception or understanding
where an object is in your mouth as you're swallowing it.
And it also is going to monitor our blood pressure, oxygen and carbon dioxide levels in the blood
and as well as responsible for sensations of touch, pain,
and thermal sensations in the ears and the throat.
The motor nerves are going to be responsible for swallowing as well as saliva secretion.
The cranial nerve 10 is our vagus nerve.
The vagus nerve is -- steps a little bit outside of the norm in that it affects parts of the body
outside of the head and neck region.
It is a mixed nerve that has both sensory nerves and motor nerves.
The sensory portion is responsible for taste in the back of the throat or at the epiglottis,
as well as proprioception of the throat and the voicebox muscles.
And it also is able to monitor blood pressure, oxygen and carbon dioxide levels
and as well receives stimuli for touch, pain, and thermal sensations of the ear
as well as sensations of your thoracic organs.
The motor neurons of the vagus nerve are responsible for things
such as swallowing, vocalization, coughing and also, autonomic activity
such as the mobility of the secretions of the gastrointestinal organs,
constrictions of your respiratory pathways and as well as your heart rate
and specifically a decreased in your heart rate.
Cranial nerve 11 is our accessory nerve.
This is a motor nerve that is responsible for movement of the head.
And our final, cranial nerve 12 is our hypoglossal nerve.
This is also a motor nerve that is responsible for muscles that are going to control speech
as well as manipulation of food and swallowing.